Centrifugal blower assembly with combined rotor and blower wheel



Jan. 25, 1966 w BOWEN 3,231,176

CENTRIFUGAL BLOWER ASSEMBLY WITH COMBINED ROTOR AND BLOWER WHEEL Filed June 30, 1964 I F G 3 INVENTOR.

WILLIAM I BOWEN BY @mwwm Hi5 ATTORNEY United States Patent 3,231,176 CENTRIFUGAL BLQWER ASSEMBLY WITH COM- BINED ROTGR AND BLOWER WHEEL William 3. Bowen, Yardley R.D., Pa., assignor to General Electric Crnnnpamy a corporation of New York Filed June 30, 1964, Ser. No. 379,099 Claims. (Cl. 230-117) The present invention relates to a centrifugal blower assembly and particularly to a design of drive motor for such an assembly where the rotor core is an integral part of the blower Wheel and the stator surrounds the blower wheel.

Air handling apparatus of the centrifugal blower type which incorporates a double-inlet blower wheel within a scroll housing is in widespread usage, particularly in the heating, ventilating and air conditioning fields. One important advantage in this type of blower assembly is the elimination of belt drives and the use of direct drive motors resulting in the adoption of the terminology motorblower unit. One disadvantage in this type of prior art has been the restriction and ensuing noise of the air flow due to the positioning of the drive motor within the blower wheel, and oftentimes within one of the air inlet openings of the scroll housing. The position of the motor would also limit the velocity of air flow or rather the air flow performance range due to its obstructing nature that produces a significant pressure loss and thus lowers the efficiency.

Also inherent in the prior art motor-blower units are low starting torques due to the imperative compactness of the motor which limits the space available for motor windings. The blower has been mounted in cantilever fashion on the motor shaft thus imposing high bearing loads and rendering of a critical nature the problem of bearing lubrication. The innermost hearing has been inaccessible thus requiring a cross-over oiler tube. In order to keep the motor bearing pressures to an acceptable limit the oil circulation hole in the journal must be located at the top and this complicates any attempt at motor standardization and it is costly in terms of extra motor lead lengths.

The principal object of the present invention is to provide an improved centrifugal blower assembly with a drive motor that has a rotor formed as an integral part of the blower wheel while the stator surrounds the blower wheel for improved starting torques and wider ranges of air flow.

A further object of the present invention is to provide a centrifugal blower assembly of the class described with a combined rotor and double inlet blower wheel where the rotor also serves as a transverse partition for the blower wheel to control the flow of air from one end of the Wheel to the other and for cooling the stator windings.

A further object of the present invention is to provide an induction motor for a centrifugal blower assembly having an annular stator surrounding the blower wheel, while the rotor is an integral part of the blower wheel adjacent the midportion thereof.

A further object of the present invention is to provide a centrifugal blower assembly of the class described with an electric motor having an annular stator surrounding the blower wheel, while the rotor is an integral part of the blower wheel, where the motor may be an induction, synchronous or a direct current motor considering the recent advances in solid state physics.

A still further object of the present invention is to provide a combined rotor and blower wheel assembly where the outer peripheral surface of the rotor is generally coextensive with the outer surface of the blower wheel.

3,231,17h Patented Jan. 25, 1966 midportion of the wheel, while the rotor core is formed as an integral part of the midportion of the blower wheel and in the plane of the stator. Thus, the rotor core also serves as a transverse partition of the blower wheel to control the flow of air from one end of the wheel to the other.

My invention will be better understood from the following description taken in conjunction with the accompanying drawing and its scope will be pointed out in the appended claims.

FlGURE l is a perspective view of a centrifugal blower assembly embodying the present invention.

FIGURE 2 is a right side elevational view of the blower assembly of FIGURE 1.

FIGURE 3 is a cross-sectional elevational view through the center of the blower assembly and taken on the line 33 of FIGURE 2, showing the nature of the combined rotor and blower wheel as well as the stator surrounding the blower wheel.

FXGURE 4 is a transverse cross-sectional elevational view of the blower assembly taken on the lines 44 of FIGURE 3 and giving a better showing of the annular stator.

Turning to a consideration of the drawing and in par-- ticular to FIGURE 1, there is shown a blower assembly 10 having a hollow housing 11 of generally volute shape including opposed scroll-shaped side walls 12 and 13. Each side wall is provided with an air inlet opening 14, and these openings are aligned with each other to be in communication with :a double inlet blower wheel 15. The blower wheel is adapted to deliver air at high velocity through an air outlet opening 15.

Attention is now directed to the cross-sectional view of FIGURE 3 where it is seen that the blower wheel 15 is a double inlet blower wheel formed in the shape of a squirrel-cage by a plurality of radially spaced longitudinally extending air moving blades 19 which are supported by a parallel grouping of four transverse ring members 20, 21, 22 and 23. Each of the outermost rings 2th and 23 is of about the same size as the air inlet opening 14 and closely spaced therefrom to provide a blower wheel with two open ends communicating with the air inlet openings ll l. The other two ring members 21 and 22 are innermost ring members adjacent the midportion of the blower wheel for cooperation with a cylindrical rotor core 25 that is an integral part of the blower wheel at the midportion of the wheel. This rotor core 25 cooperates with an annular stator 26 as is best seen in FIGURES 3 and 4 as being fixed or built into the blower housing 11. The rotor 25' and stator 26 represent an induction motor such as a shaded pole permanent split capacitor, capacitor start or split phase induction motor that are commonly employed in fan motors, electrical appliances and the like. The stator surrounds the blower wheel in the plane of the rotor core 25. A supporting shaft 28 extends though the center of the rotor core 25 and projects beyond the end rings 29 and 23 of the blower wheel to provide journal portions 29 and 3% which are adapted to seat within motor bearings 31 and 32 respectively. Each bearing is formed as part of a mounting strap 33 that is fastened across each inlet opening 14 to provide support for the blower wheel 3 15 without unduly obstructing the flow of air into the blower housing 11 through the openings.

Notice that the rotor core 25 is shown as a cylindrical member of solid construction having an outer surface 35 that is generally coextensive with the outer surface or periphery of the blower wheel 15 and is provided with a plurality of spaced transverse metal bars 27 connected between the rings 21 and 22. Both the rotor core 25 and the stator 26 are formed of a plurality of laminations of the type generally found in squirrel cage induction motors. Moreover, the rotor core 25 serves as a transverse partition of the blower wheel to control the passage of air from one end of the wheel to the other thereby establishing two single inlet wheels 37 and 38.

As is best seen in FIGURE 4, the stator 26 is an annular member that is provided with a group of four pole pieces 40-43 on the inner periphery thereof although admittedly any number of poles from two to ten are conceivable. The poles are equally spaced from each other while being in close running relationship with the rotor core 25 with a small air gap 45 therebetween as is well understood by those working in the motor art. Stator windings 46 encompass the pole pieces 4l-43 and they constitute the main winding and the starting winding for the motor. The annular stator 2d is built into the housing 1?. of the blower assembly as is best shown in FIG- URES 1 and 3 by forming a circular recess 49 in which the stator is positioned so that the periphery of the blower wheel 15 is closely spaced with the scroll-shaped walls of the blower housing 11 especially at the top of the housing as is viewed in FIGURE 3, although not quite so much at the lower portion of the housing.

Having described above my invention of a centrifugal blower assembly where the rotor is integral with the blower wheel and the stator encircles the blower wheel, it will readily be apparent to those skilled in this art that I have improved the starting torque of the motor by increasing'the normal size of the rotor, both motor bearings have been located in accessible positions for better lubrication, the maximum motor bearing load has been greatly reduced over a cantilever support for the blower wheel, the voltage stability has been increased by the use of more copper in the rotor that is possible with more available space, and the larger stator diameters will improve the cooling of the stator windings.

Modifications of this invention will occur to those skilled in this art, therefore, it is to be understood that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention as claimed.

What I claim as new and desire Patent of the United States is:

1. A centrifugal blower comprising a housing of generally volute shape including opposed scroll sides, means defining a pair of aligned air intake openings through said scroll sides to the interior of said housing, a blower wheel within said housing having blades forming a cage structure, a supporting shaft through the center of the wheel, bearing members positioned in the intake openings and supporting the blower wheel shaft therein, means defining an outlet from said housing, and an electric motor for driving the blower wheel, said motor including an annular stator and a cylindrical rotor core, the rotor being an integral part of the blower wheel, located within the midportion thereof and concentric therewith, the rotor having an outer surface that is generally coextensive with the outer surfaces of the cage structure of the blOWer to secure by Letters wheel, the stator being located within the blower housing and surrounding the rotor.

2. A centrifugal blower assembly comprising a double inlet blower wheel, a blower housing of generally volute shape including opposed scroll side walls with an air intake opening in each side wall leading into the interior of the housing, an outlet opening extending between the side walls, and an electric motor driving the blower wheel, said motor comprising an outer stator built into the blower housing and an inner rotor formed as an integral part of the blower wheel and being adjacent the midportion thereof, the rotor including a central supporting shaft extending therethrough, and a mounting bracket located in each air intake opening, each bracket including a bearing member in which the shaft is journalled, the rotor serving as a transverse partition within said blower wheel controlling the fiow of air from one end thereof to the other.

3. A centrifugal blower assembly comprising a housing of generally volute shape having a pair of side walls with an air inlet opening in each, an outlet opening in the housing extending between the side walls, and a double inlet blower wheel having a central supporting shaft, and bracket means for supporting the shaft so that the blower wheel is located within the housing, and a drive motor for the blower wheel; the invention comprising a drive motor with an annular stator built into the blower housing and a solid rotor core formed as an integral part of the blower wheel adjacent the midportion thereof, the outer surface of the rotor being generally coextensive with the outer surface of the blower wheel, the rotor corev serving as a transverse partition for the blower wheel.

4. A centrifugal blower assembly comprising a housing of generally volute shape having a pair of side walls with an air inlet opening in each, an outlet opening in the housing extending between the side walls, and a double inlet blower Wheel having a central supporting shaft, and bracket means for supporting the shaft so that the blower wheel is located within the housing; the invention comprising an induction motor with an annular stator built into the blower housing and a solid rotor core formed as an integral part of the blower wheel adjacent the midportion thereof, said rotor core serving as a transverse partition for the blower wheel to control the flow of air from one end thereof to the other.

5. A centrifugal blower assembly comprising a housing of generally volute shape and a double inlet blower wheel; the invention comprising a split-phase induction motor with an annular stator built into the blower housing and a solid rotor core formed as an integral part of the blower wheel adjacent the midportion thereof, said rotor core serving as a transverse partition for the blower wheel to control the flow of air from one end thereof to the other, the stator and rotor are each formed by joining a plurality of metal laminations, the annular stator including at least two equally spaced poleson the interior periphery thereof with stator windings encircling each poie, while the solid rotor core is a squirrel cage type rotor having a plurality of spaced transverse bars on the outer surface of the rotor.

References Cited by the Examiner UNITED STATES PATENTS l.825,036 9/1931 Young. 2,185,740 1/1940 Smith. 2,193,408 3/1940 Knight.

ROBERT M. WALKER, Primary Examiner. 

1. A CENTRIFUGAL BLOWER COMPRISING A HOUSING OF GENERALLY VOLUTE SHAPE INCLUDING OPPOSED SCROLL SIDES, MEANS DEFINING A PAIR OF ALIGNED AIR INTAKE OPENINGS THROUGH SAID SCROLL SIDES TO THE INTERIOR OF SAID HOUSING, A BLOWER WHEEL WITHIN SAID HOUSING HAVING BLADES FORMING A CAGE STRUCTURE, A SUPPORTING SHAFT THROUGH THE CENTER OF THE WHEEL, BEARING MEMBERS POSITIONED IN THE INTAKE OPENINGS AND SUPPORTING THE BLOWER WHEEL SHAFT THEREIN, MEANS DEFINING AN OUTLET FROM SAID HOUSING, AND AN ELECTRIC MOTOR FOR DRIVING THE BLOWER WHEEL, SAID MOTOR INCLUDING AN 